How to set appFolder so that export does not wipe it out in designer.js

How to set appFolder so that export does not wipe it out in designer.js

I need to set the path for the application. Modifying (against the rules) ext.application in the generated designer.js to include:
appFolder: '/myurl/app',
works but is wiped out every time I hit export (of course).

Is there a property in designer I'm missing?

I noticed someone esle reporting a bug that the following modification to the calling .html doesn't work and should, but the bug was closed saying that modifying appFolder as described above worked (but is not the solution).
<script type="text/javascript">
Ext.Loader.setConfig({ enabled: true });
Ext.Loader.setPath('Foo', 'foo/app');
</script>
<script type="text/javascript" src="foo/app/Application.js"></script>

Work around would be to create a index.js that is a copy of designer.js and that you've altered to include appFolder. In general the designer.js file is an example that shows all of your views on the same screen but in practice you wouldn't only use this as an idea. Export will not overwrite index.js.